Working with Raster Data - Desktop GIS: Mapping the Planet with Open Source Tools - page 59

Another way to get the same information is with gdalinfo , a utility that
comes with GDAL and is included in FWTools: 3

$ gdalinfo o47113g1.tif
Driver: GTiff/GeoTIFF
Size is 4769, 6920
Coordinate System is:
PROJCS["NAD27 / UTM zone 12N",
GEOGCS["NAD27",
DATUM["North_American_Datum_1927",
SPHEROID["Clarke 1866",6378206.4,294.9786982139006,
AUTHORITY["EPSG","7008"]],
AUTHORITY["EPSG","6267"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4267"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-111],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AUTHORITY["EPSG","26712"]]
Origin = (339751.702040000003763,5305307.515394000336528)
Pixel Size = (2.438400000000000,-2.438400000000000)
...

We didn't include all the output from gdalinfo ; we included just enough
for you to see the projection information. If you recall earlier, I told
you that when downloading, we needed the . tfw file, which is actually
the world file for the raster. The fact that the projection information
is reported by gdalinfo means that it is a GeoTIFF and contains not
only the coordinate information needed to properly display it but also
the projection information. You don't need the world file for a GeoTIFF.
The fact that the DRG was a GeoTIFF wasn't readily apparent from the
website, so we played it safe and downloaded the world file as well. For-
tunately, we didn't waste much bandwidth downloading it since world
files are only a few hundred bytes in size.

Let's return to our global theme now and view a raster mosaic, cour-
tesy of NASA Visible Earth. 4 If you want to follow along, you can fetch

3. If it's not already on your system, see Section B.7 , FWTools, on page 295 for informa-
tion on installing FWTools.
4. The ev11612_land_ocean_ice_8192 image is owned and provided by NASA. The image
was obtained from the Visible Earth ( http://visibleearth.nasa.gov ) and developed by the Earth